1. Field of the Invention
This invention relates generally to the testing of piston rings or the like, and is more particularly concerned with a method and apparatus for testing rings by pressurizing a cylinder with fluid and monitoring the dissipation of the pressure.
2. Discussion of the Prior Art
Piston driven internal combustion engines depend on a tight seal between the piston and the cylinder wall to prevent the expanding gases from "blowing by" the piston. With a close fitting seal between the piston and the cylinder wall, the exploding gases force the piston to move within the cylinder to transmit energy to the crankshaft. The seal between the piston and the cylinder is effected by one or more piston rings floating in circumferential grooves around the body of the piston. When piston rings are excessively worn they do not adequately seal, and there is a loss of proper pressure within a cylinder. The prior art includes means for measuring the compression in a cylinder as the piston moves up in the cylinder; but, when one needs to know if the piston rings are sealing properly, the pistons must be removed from the cylinder, and the rings directly inspected.
There has been some effort at determining the condition of the rings without the necessity of removal of the piston, such efforts being as shown by the patents to Harpst (U.S. Pat. No. 1,337,132) and to Morgan et al. (No. 2,003,949). In both of these patents, the cylinder is pressurized in an effort to determine if the cylinder can retain the fluid under pressure. However, in both of these patents the cylinder is pressurized through the spark plug opening or the like, and retention of the pressure is dependent on the piston rings and the valves. As a result, one cannot be sure of the particular problem without a direct inspection of the rings and the valves
Thus, the prior art does not provide a method or apparatus for testing the seal effected by the piston rings without removal of the piston from the cylinder for direct inspection of the rings.